Speaker
Prof.
Bruno Coppi
(M.I.T.)
Description
In the context of a two-fluid theory of magnetic reconnection [1], when the longitudinal electron thermal conductivity is relatively large, the perturbed electron temperature tends to become singular [2] in the presence of a reconnected field component and an electron temperature gradient. A transverse thermal diffusivity is introduced in order to remove this singularity while a finite ``inductivity’’ can remove the singularity of the corresponding transverse plasma displacement [1]. Then i) a new ``magneto-thermal reconnection’’ producing mode, driven by the electron temperature gradient, and involving a considerable range of scale distances is found [3]; ii) the characteristic widths of the layers in which magnetic reconnections takes place remain significant even when the macroscopic distances involved in the process are very large; iii) the phase velocities of the modes that are found can be both in the direction of the electron diamagnetic velocity as well as those in the opposite (ion) direction. A numerical solution of the complete set of equations has been carried out and followed by a simplified analytical reformulation of the problem. The mode growth rate is related to the effects of a finite viscous diffusion coefficient or to those of a small electrical resistivity.
The features that can lead to a possible explanation of the fact that high energy particle populations are produced during reconnection events involve mode-particle resonances producing the transfer of energy to super-thermal particle populations [4] and the spatial near-singularity of the electron temperature that can enhance the thermal energy of particles in one region while depleting that of particles in a contiguous region [3].
The low collisionality modes that produce magnetic reconnection can extract angular momentum from the plasma column and thereby sustain a ``spontaneous rotation’’ [5] of it. This process is to be considered in addition to that associated with electrostatic modes excited at the edge of the plasma column [5]. Supported by the U.S. DOE, award DE-FG02-03ER54700.
[1]B. Coppi, Phys. Fluids 8, 2273 (1965).
[2]B. Coppi, B. Basu, P. Montag, et al. Nucl. Fus., 55, 093018 (2015).
[3]B. Coppi, MIT (LNS) Report HEP 15/06 (2015). In print for Fizika Plazmy.
[4]B. Coppi, L. Sugiyama, J. Mark and G. Bertin Ann. Phys. 119, 370 (1979).
[5]B. Coppi, Nucl. Fus. 42, (2002).
| Country or International Organization | United States |
|---|---|
| Paper Number | TH/P1-33 |
Primary author
Prof.
Bruno Coppi
(M.I.T.)
Co-authors
Dr
Alexander Fletcher
(M.I.T.)
Dr
Bamandas Basu
(M.I.T.)
Linda Sugiyama
(M.I.T.)
Dr
Ryan L. White
(M.I.T.)
